Method and apparatus for filling fuel gas in a gas turbine

ABSTRACT

The gas turbine fuel gas filling apparatus comprises a fuel main valve, a fuel valve, an inert gas purge valve, and a pressure detector for detecting a pressure in the fuel line. The fuel main valve is gradually opened, and fixed to a valve opening at a time when a predetermined first pressure condition is established. Pressure is measured after lapse of a predetermined time. The fuel main valve is gradually opened until a second pressure condition is established. Pressure is measured upon a completion of gas-filling. With establishment of a third pressure condition, the inert purge relief valve is closed. With establishment of a fourth pressure condition, the fuel main valve is fully opened.

FIELD OF THE INVENTION

[0001] The present invention in general relates to a method and apparatus for filling fuel gas in a gas turbine. More particular, this invention relates to a method and apparatus for filling fuel gas in a gas turbine which can supply a predetermined fuel gas flow in accordance with the system state, by automatically changing open-close timings such as of a purge relief valve and a gas-filling opening of a fuel main valve, depending on an actual state of gas-filling, and by which adjustment work can be saved.

BACKGROUND OF THE INVENTION

[0002] In a gas-fired gas turbine, it is necessary to perform a gas-filling process with respect to the fuel line (from a fuel main valve (or fuel gas supply valve) to a fuel shutoff valve) before the startup. This process is necessary, after a long-term shutdown of or inspection to the gas turbine where the fuel line should have been filled with an inert gas such as nitrogen, for replacement of the inert gas with a fuel gas at the startup to avoid supplying a combustor nozzle with mixture of fuel gas and inert gas, to thereby prevent a failure of light-up. The fuel main valve, to be open in usual run, should have a possibly reduced pressure loss, and hence a ball valve is employed therefore.

[0003] An automated unit for a series of sequential actions for such a gas-filling is adapted to simply open and close a fuel main valve (with a constant gas-filling opening) and a purge valve, with lapse of time. In a certain case, as the fuel main valve, there is employed no ball valve, but a dedicated valve apparatus that enables a delicate opening setting. However, such a case is out of the scope of the present invention.

[0004] A conventional automated gas-filling sequence performs mere opening and closing respectively of a fuel main valve (with a constant gas-filling opening) and a purge valve, with lapse of time (without feeding back a valve condition), so that the fuel main valve has an opening interval variable with associated system states (line length, diameter, configuration, etc.), resulting in troublesome on-site adjustment for setting the interval, as a problem.

[0005] Moreover, the fuel main valve (ball valve) has an opening characteristic on which a delicate opening setting is difficult, and fails to follow a uniform gas-filling operation, due to different system states, such as inline temperature and pressure for gas-filling and flow characteristic of the fuel main valve, as another problem.

[0006] Further, the fuel main valve, which is difficult of a delicate opening setting, causes a fuel gas to vigorously outflow when opened, with an impact that generates noises and may give damages to various devices, as another problem.

[0007] Further, there is an associated tendency to release unburnt gases into the atmosphere until a predetermined time interval elapses, wasting fuel gas, which is non-economical, and unfavorable also in respect of environmental protection, as another problem.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide a method and apparatus for filling fuel gas in a gas turbine that is allowed, in a gas turbine plant provided with a fuel main valve comprised of a ball valve, to supply a predetermined gas flow in an adequate manner in accordance with a system state, thereby implementing adjustment labor saving and cost-down, noise reduction, reduction in degree of impact to a variety of devices, and the like.

[0009] The gas turbine fuel gas filling apparatus according to one aspect of this invention comprises a fuel main valve installed upstream of a fuel line and comprised of a ball valve, a fuel valve installed downstream of the fuel line and upstream of a combustor nozzle, an inert gas purge valve for purging out of the fuel line an inert gas supplied into the fuel line by a supply unit of the inert gas, and a pressure detector for detecting a pressure in the fuel line. Furthermore, the fuel main valve is gradually opened to be fixed to a valve opening at a time point when a predetermined first pressure condition of the fuel line is established; after lapse of a predetermined time, again checking a state of pressure, the fuel main valve is gradually opened until a second pressure condition is established; the state of pressure is checked also upon a completion of gas-filling; the inert gas purge release valve is closed with establishment of a third pressure condition; and the fuel main valve is fully opened with establishment of a fourth pressure condition. A predetermined fuel gas flow is thereby adequately supplied to the fuel line in accordance with a system state.

[0010] Further, the number of times the pressure condition are set and the duration for which the measurement is performed are increased or decreased based on the system state.

[0011] The gas turbine fuel gas filling apparatus preferably further comprises a control valve for correcting a flow rate of gas outflowing from the fuel main valve in dependence on a state of temperature and pressure in the fuel line.

[0012] The gas turbine fuel gas filling apparatus preferably further comprises a combination of a bypass valve and an orifice for correcting a flow rate of gas outflowing from the fuel main valve in dependence on a state of temperature and pressure in the fuel line.

[0013] Furthermore, it is preferable that the fuel gas is the natural gas.

[0014] Furthermore, it is preferable that the inert gas is nitrogen gas.

[0015] The method of filling fuel gas in a gas turbine, which gas turbine comprises a fuel line for supplying the fuel gas; a fuel main valve provided on said fuel line; a fuel valve provided on said fuel line on the downstream of said fuel main valve; a combustor nozzle as an outlet for the fuel gas; an inert gas supply for supplying an inert gas to said fuel line; an inert gas purge valve for purging out the inert gas out of said fuel line; and a pressure detector for detecting a pressure in said fuel line, according to another aspect of this invention comprises following steps.

[0016] 1) Gradually opening said fuel main valve and simultaneously checking the pressure in said fuel line detected by said pressure detector.

[0017] 2) Stopping opening of said fuel main valve when the pressure detected by said pressure detector has reached a predetermined first pressure.

[0018] 3) Waiting for lapse of a predetermined time.

[0019] 4) Checking the pressure in said fuel line detected by said pressure detector and determining whether the pressure detected by said pressure detector has reached a predetermined second pressure.

[0020] 4) Gradually further opening said fuel main valve if the pressure detected by said pressure detector has not reached the second pressure.

[0021] 5) Checking the pressure in said fuel line detected by said pressure detector and determining whether the pressure detected by said pressure detector has reached a predetermined third pressure.

[0022] 6) Closing said inert gas purge release valve if the pressure detected by said pressure detector has reached the third pressure.

[0023] 7) Checking the pressure in said fuel line detected by said pressure detector and determining whether the pressure detected by said pressure detector has reached a predetermined fourth pressure.

[0024] 8) Fully opening said fuel main valve if the pressure detected by said pressure detector has reached the fourth pressure.

[0025] Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a time chart describing gas admission of a fuel gas supply system of a gas turbine fuel gas filling apparatus according to a first embodiment of the invention;

[0027]FIG. 2 is a diagram illustrating the fuel gas supply system of the gas turbine fuel gas filling apparatus;

[0028]FIG. 3 is a diagram illustrating a fuel gas supply system of a gas turbine fuel gas filling apparatus according to a second embodiment of the invention; and

[0029]FIG. 4 is a diagram illustrating a fuel gas supply system of a gas turbine fuel gas filling apparatus according to a third embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Preferred embodiments of the gas turbine fuel gas filling apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. However, this invention is not limited by these embodiments.

[0031]FIG. 1 is a time chart describing gas admission of the fuel gas supply system of the gas turbine fuel gas filling apparatus according to a first embodiment of the invention. The width of the hatched portion indicates an amount for which a valve is opened. The numbers (1) to (7) indicate operations. FIG. 2 is a diagram illustrating the fuel gas supply system of the gas turbine fuel gas filling apparatus.

[0032] The present invention relates to filling of a fuel gas (for example, natural gas) in a fuel line 1, between a fuel main valve 2 and a fuel shutoff valve 3. Following valves are used for filling the gas. That is, a nitrogen purge relief valve 4 installed near the fuel main valve 2; and a nitrogen purge relief valve 5 installed in a release system to the atmosphere. Nitrogen purge supply valves 6, 7 are for supply of nitrogen gas to he fuel line 1.

[0033] A pressure gauge 8, installed as a pressure detector in the fuel line 8, monitors a condition of fuel supply to the fuel line 8, and feeds back the pressure data to an inching opening control of the fuel main valve 2. The fuel line 1 is provided with a strainer 9 for fuel filtration, a fuel relief valve 10 for excessive gas fuel to be released into the atmosphere, and so on. For control such as of valves 2 to 7 and 10 as well as calculations of pressure data, there is a not shown controller configured to execute automatic processing.

[0034] A method of filling the gas will now be described with reference to FIG. 1. At a start of gas filling, the fuel main valve 2 is gradually opened by inching (operation (2)), and fixed to a valve opening at a time when a predetermined pressure condition (i.e. an inlet pressure of the fuel shutoff valve 3 to be measured by the pressure gauge 8, as used herein) is established (operations (3) and (4)). After lapse of a predetermined time, the state of pressure is checked again (operation (4), and the fuel main valve 2 is gradually opened until a subsequent pressure condition becomes established (operations (4) and (5)). The state of pressure is checked upon a completion of gas-filling, as well, and with establishment of a subsequent pressure condition, the nitrogen purge relief valve 5 is closed (operation (6)), and then with a subsequent pressure condition established, the fuel main valve 2 is fully opened (operation (7)).

[0035] In this manner, the state of pressure is checked at the respective points, thereby permitting an optimal gas-filling in accordance with a system state. Effective prevention is thus possible against conventional drawbacks, such as release of unburnt gases that might have been excessive in gas-filling, impact sounds due to rushing fuel gas, and shocks of the impact to various devices.

[0036] According to the first embodiment, a gas turbine fuel gas filling apparatus allows the flow rate of outflowing gas to be optimized in gas-filling, thereby permitting cost-down, noise reduction, and a reduced shock to devices.

[0037] Without the need to perform an on-site adjustment for conventional opening interval setting of fuel main valve 2, there can be achieved an adjustment labor saving

[0038] The first embodiment employs nitrogen gas as an inert gas. The inert gas, however, is not limited thereto, and may well be another that is poorly reactive to fuel gas. The strainer 9, fuel relief valve 10, nitrogen purge relief valve 5, nitrogen purge supply valve 6, 7 and the like may be voluntary in number, as circumstances require, and not limited to the illustrated example.

[0039] Although the description has been made of a fuel gas filling in a gas turbine plant, the present invention may have other applications such as water-filling of a steam turbine circulation water or condenser water chamber.

[0040]FIG. 3 is a diagram illustrating a fuel gas supply system of the gas turbine fuel gas filling apparatus according to the second embodiment of the invention. Although in the first embodiment a pressure condition by the pressure gauge 8 is fed back for an inching operation to open the fuel main valve 2, the second embodiment employs, in addition to the same, a pressure-temperature gauge 14 as a pressure and temperature detector for measuring pressure and temperature conditions of a fuel line 1 to provide measurement values to be based on for automatic control of a control valve 12, thereby controlling the flow rate of gas outflowing from a fuel main valve 2. The remaining arrangement and actions are analogous to those of the first embodiment, and their description is omitted.

[0041] According to the second embodiment, a gas turbine fuel gas filling apparatus is adapted, by provision of the control valve 12 and pressure-temperature gauge 14, to optimize the flow rate of outflowing gas in gas-filling, thereby permitting cost-down, noise reduction, and a reduced shock to devices.

[0042]FIG. 4 is a diagram illustrating a fuel gas supply system of the gas turbine fuel gas filling apparatus according to the third embodiment of the invention. Although in the first embodiment a pressure condition by the pressure gauge 8 is fed back for an inching operation to open the fuel main valve 2, the third embodiment employs, in addition to the same, a pressure-temperature gauge 14 as a pressure and temperature detector for measuring pressure and temperature conditions of a fuel line 1 to provide measurement values to be based on for operation of bypass control valves 15, 17 and orifices 16, 18, thereby controlling the flow rate of gas outflowing from a fuel main valve 2. The remaining arrangement and actions are analogous to those of the first embodiment, and their description is omitted.

[0043] According to the third embodiment, a gas turbine fuel gas filling apparatus is adapted, by provision of the pressure-temperature gauge 14, bypass control valves 15, 17, and orifices 16, 18, to optimize the flow rate of outflowing gas in gas-filling, thereby permitting cost-down, noise reduction, and a reduced shock to devices.

[0044] Thus, according to one aspect of this invention, the gas turbine fuel gas filling apparatus comprises a fuel main valve installed upstream of a fuel line and comprised of a ball valve, a fuel valve installed downstream of the fuel line and upstream of a combustor nozzle, an inert gas purge valve for purging out of the fuel line an inert gas supplied into the fuel line by a supply unit of the inert gas, and a pressure detector for detecting a pressure in the fuel line. Furthermore, the fuel main valve is gradually opened to be fixed to a valve opening at a time point when a predetermined first pressure condition of the fuel line is established; after lapse of a predetermined time, again checking a state of pressure, the fuel main valve is gradually opened until a second pressure condition is established; the state of pressure is checked also upon a completion of gas-filling; the inert gas purge release valve is closed with establishment of a third pressure condition; and the fuel main valve is fully opened with establishment of a fourth pressure condition, whereby a predetermined fuel gas flow is adequately supplied to the fuel line in accordance with a system state.

[0045] Accordingly, by optimization of the flow rate of outflowing gas in gas-filling, there can be implemented cost-down, noise reduction, a reduced shock to devices, and the like. Further, without the conventional need of on-site adjustment for opening interval setting of a fuel main valve, there can be saved adjustment labor.

[0046] Further, the number of times the pressure condition are set and the duration for which the measurement is performed are increased or decreased based on the system state. Thereby, depending on a system state of a turbine plant, an adequate condition setting is allowed, permitting a smoother gas-filling operation.

[0047] The gas turbine fuel gas filling apparatus further comprises a control valve for correcting a flow rate of gas outflowing from the fuel main valve in dependence on a state of temperature and pressure in the fuel line. Thereby, the flow rate of gas outflowing from the fuel main valve can be set more delicately.

[0048] The gas turbine fuel gas filling apparatus further comprises a combination of a bypass valve and an orifice for correcting a flow rate of gas outflowing from the fuel main valve in dependence on a state of temperature and pressure in the fuel line. Thereby, the flow rate of gas outflowing from the fuel main valve can be set more delicately.

[0049] Furthermore, the fuel gas is the natural gas. This allows an easy application to a gas turbine plant using a general-purpose fuel.

[0050] Furthermore, the inert gas is nitrogen gas. This allows an easy and inexpensive application to a gas turbine plant using a natural gas fuel.

[0051] Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth. 

What is claimed is:
 1. A gas turbine fuel gas filling apparatus comprising: a fuel main valve installed upstream of a fuel line and comprised of a ball valve; a fuel valve installed downstream of said fuel line and upstream of a combustor nozzle; an inert gas purge valve for purging out of said fuel line an inert gas supplied into said fuel line by a supply unit of the inert gas; and a pressure detector for detecting a pressure in said fuel line, wherein said fuel main valve is gradually opened to be fixed to a valve opening at a time point when a predetermined first pressure condition of the fuel line is established; after lapse of a predetermined time, again checking a state of pressure, said fuel main valve is gradually opened until a second pressure condition is established; the state of pressure is checked also upon a completion of gas-filling; said inert gas purge release valve is closed with establishment of a third pressure condition; and said fuel main valve is fully opened with establishment of a fourth pressure condition, whereby a predetermined fuel gas flow is adequately supplied to said fuel line in accordance with a system state.
 2. The gas turbine fuel gas filing apparatus according to claim 1 , wherein the number of times the pressure condition are set and the duration for which the measurement is performed are increased or decreased based on the system state.
 3. The gas turbine fuel gas filling apparatus according to claim 1 , further comprising a control valve for correcting a flow rate of gas outflowing from said fuel main valve in dependence on a state of temperature and pressure in said fuel line.
 4. The gas turbine fuel gas filling apparatus according to claim 1 , further comprising a combination of a bypass valve and an orifice for correcting a flow rate of gas outflowing from said fuel main valve in dependence on a state of temperature and pressure in said fuel line.
 5. The gas turbine fuel gas filling apparatus according to claim 1 , wherein the fuel gas is a natural gas.
 6. A gas turbine fuel gas filling apparatus according to claim 1 , wherein the inert gas is nitrogen gas.
 7. A method of filling fuel gas in a gas turbine, which gas turbine comprises a fuel line for supplying the fuel gas; a fuel main valve provided on said fuel line; a fuel valve provided on said fuel line on the downstream of said fuel main valve; a combustor nozzle as an outlet for the fuel gas; an inert gas supply for supplying an inert gas to said fuel line; an inert gas purge valve for purging out the inert gas out of said fuel line; and a pressure detector for detecting a pressure in said fuel line, the method comprising the steps of: gradually opening said fuel main valve and simultaneously checking the pressure in said fuel line detected by said pressure detector; stopping opening of said fuel main valve when the pressure detected by said pressure detector has reached a predetermined first pressure; waiting for lapse of a predetermined time; checking the pressure in said fuel line detected by said pressure detector and determining whether the pressure detected by said pressure detector has reached a predetermined second pressure; gradually further opening said fuel main valve if the pressure detected by said pressure detector has not reached the second pressure, checking the pressure in said fuel line detected by said pressure detector and determining whether the pressure detected by said pressure detector has reached a predetermined third pressure; closing said inert gas purge release valve if the pressure detected by said pressure detector has reached the third pressure; checking the pressure in said fuel line detected by said pressure detector and determining whether the pressure detected by said pressure detector has reached a predetermined fourth pressure; and fully opening said fuel main valve if the pressure detected by said pressure detector has reached the fourth pressure.
 8. The method according to claim 7 , wherein the number of times the pressure condition are set and the duration for which the measurement is performed are increased or decreased based on the system state.
 9. The method according to claim 7 , further comprising a step of correcting a flow rate of gas outflowing from said fuel main valve in dependence on a state of temperature and pressure in said fuel line.
 10. The method according to claim 7 , wherein the fuel gas is a natural gas.
 11. The method according to claim 7 , wherein the inert gas is nitrogen gas. 